Chou-Fasman (bend assignment)
To identify a bend at residue number j, calculate the following value
p(t) = f(j)f(j+1)f(j+2)f(j+3)
where the f(j+1) value for the j+1 residue is used, the f(j+2) value
for the j+2 residue is used and the f(j+3) value for the j+3 residue
is used. If: (1) p(t) > 0.000075; (2) the average value for
P(turn) > 1.00 in the tetrapeptide; and (3) the averages for the
tetrapeptide obey the inequality P(a-helix) < P(turn) > P(b-sheet),
then a beta-turn is predicted at that location.